This invention relates to a safety element for a fuze of a projectile to which no spin or only slight spin is imparted upon firing.
STANAG 4187 (NATO military standard) and MIL-STD 1316 (German military standard) require that fuze safety systems comprise at least two mutually independent safety devices, each of which prevents an unintentional safety release and thus a detonation of the ammunition by the fuze system. The conditions which make possible for at least two safety elements to respond must be derived from different, external environmental forces.
According to the classical case for ammunition fired from weapon barrels with a spin, the acceleration upon firing and the centripetal force are used as the safety release criteria. These two environmental forces are very large in relation to other forces which may be produced during storage, transport or similar effects and are entirely sufficient to provide for the safety of such fuze systems. An example is the 35 mm barrel ammunition having a firing acceleration of approximately 70,000 g and a rotary velocity of approximately 70,000 rpm.
Fuzes contained in ammunition which is fired without spin or only with a very slight spin are more difficult to secure. For example, in case of mechanical mortar fuzes an insert is used as the second safety release which is removed by the crew prior to loading. Thus, from the moment of such removal until firing only a single safety is operative (such as a dual pin system) and thus the above noted requirements are not complied with.
The case is similar for a DM 781 fuze of the 120 mm multipurpose tank ammunition. In such a fuze the carrier of the transfer charge is secured only with a dual pin system which again does not satisfy the above-discussed requirements.